The present invention relates to an imprinting machine that transfers a pattern of a mold onto an object.
The photolithography technology has conventionally been widespread as a fine processing technology in the semiconductor process. However, the photolithography requires a projection exposure step and a development step to transfer a desired shape onto the object.
The nanoimprint technology is proposed, for example, in U.S. Pat. Nos. 6,482,742 and 6,517,977, which presses or stamps a mold having a fine concave-convex pattern against an object or a substrate, thereby transferring the concave-convex pattern without the projection exposure or development step. Japanese Patent Application, Publication No. 2000-194142 discloses at paragraphs 0012-0020 and in FIGS. 1 and 2, etc., a transfer of a concave-convex pattern without strongly pressing the mold against the object.
This method applies liquid photopolymerizing resin onto a substrate of the object, and presses the mold against the photopolymerizing resin. Then, this method irradiates the light through the mold, cures the photopolymerizing resin, and transfers the concave-convex pattern of the mold. The mold is made, for example, of glass that allows the light to pass through the mold.
This method has advantages in that the mold does not have to be strongly pressed against the object and thus the mold and the object are less likely to get damaged, and the time period required for the pattern transfer is relatively short. This method is expected to transfer a pattern having a critical dimension (“CD”) of several tens nanometers.
A step-and-flash transfer technology is proposed as an application of this method, which sequentially changes a pattern transfer position relative to the object.
The nanoimprint technology requires the mold and the object, such as a substrate, to be arranged in parallel. The non-parallel pattern transfer causes uneven transfer pressure and height, or damages of part of the mold due to a so-called end contact in which only one end of the mold contacts the substrate.
When the nanoimprint technology is used to manufacture a semiconductor chip, the mold size is as large as one chip or several millimeters square to several centimeters square. It is therefore very difficult to press such a sized mold against the object precisely while maintaining the mold and the object in parallel.
Usually, pattern transfers several times are necessary to manufacture the semiconductor chip, etc., and all the transfer patterns should be precisely overlaid. Therefore, a highly precise alignment between the mold and the substrate is necessary for each pattern transfer.
A conventional semiconductor exposure apparatus fixes a photomask having a pattern in place, and aligns the photomask with the object precisely by controlling a position of a fine movement stage on which the object is placed.
On the other hand, the nanoimprint technology brings the mold into contact with the object, and when the mold is being pressed against the object, for example, the mold is subject to a position shifting force in a direction horizontal to the direction in which the mold is pressed against the object. In addition, the end contact causes a deformation of the holding mechanism of the mold and a positional shift of the mold.
In other words, even a precise alignment between the mold and the object before the mold is pressed against the object does not guarantee that arrangement while the mold is actually being pressed against the object.